P040A

EGR Temperature Sensor A Circuit

Q: Is it safe to drive with P040A?

Generally yes — it's an emissions sensor fault and rarely affects drivability. Get it fixed before an emissions test, though.

Q: Can I just clear P040A?

It will clear, but returns until the EGR temperature sensor or its wiring is repaired.

EGR / emissions Generic OBD-II Medium

What it means

P040A means the engine computer detected a circuit fault in EGR temperature sensor A, which monitors the temperature of recirculated exhaust gas. This is a sensor-circuit code — not the EGR valve — so it usually has little effect on drivability but will keep the check-engine light on and can fail an emissions test. It most often traces to the sensor, its wiring, or carbon fouling.

Medium

Can I keep driving? Safe to drive; this is an emissions-monitor fault with little effect on how the car runs, though it may fail an emissions test.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Appears alongside · share of P040A scans

P2BAEin 53.8% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Often no noticeable change in how the vehicle drives
May fail an emissions/readiness test
Possible slight drop in fuel economy on some vehicles

Common causes

Most likely first

Faulty EGR temperature sensor ALikely
Open, shorted, or corroded wiring in the sensor circuitCommon
Loose or corroded connector at the sensorCommon
Heavy carbon buildup around the sensor affecting its readingLess often
Failed engine control module (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the code is the EGR temperature sensor A circuit (not the EGR valve itself).
Inspect the sensor connector and wiring for damage or corrosion.
Check the sensor's resistance/signal against temperature spec with a scan tool.
Clean carbon from the sensor tip if fouled, or replace the sensor if it's out of spec. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P040A?+

Generally yes — it's an emissions sensor fault and rarely affects drivability. Get it fixed before an emissions test, though.

Can I just clear P040A?+

It will clear, but returns until the EGR temperature sensor or its wiring is repaired.

Read & clear P040A yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX